PromucFlow_constructor/app
Rahul Barwal a801a19581
feat: Implement empty meta widget generation for handling empty data scenarios (#40886)
## Description
<ins>Problem</ins>

Errors appeared in the console when the List widget in edit mode
received an empty array as data.

<ins>Root cause</ins>

In edit mode, the List widget uses template widgets to create meta
widgets. When the list becomes empty, meta widgets are not generated,
but template widgets with `currentItem` bindings remain. Since
`currentItem` requires meta widgets for evaluation, this results in
errors.

<ins>Solution</ins>

This PR handles the generation of empty meta widgets when the List
widget receives empty data, ensuring `currentItem` bindings don’t break.
It introduces a `generateEmptyMetaWidgets` method in
`MetaWidgetGenerator`, enhances the List widget to track and respond to
empty data states, and resets the meta widget cache when transitioning
between empty and non-empty states.

Fixes #`Issue Number`  
_or_  
Fixes https://github.com/appsmithorg/appsmith/issues/31925
> [!WARNING]  
> _If no issue exists, please create an issue first, and check with the
maintainers if the issue is valid._

## Automation

/ok-to-test tags="@tag.List"

### 🔍 Cypress test results
<!-- This is an auto-generated comment: Cypress test results  -->
> [!TIP]
> 🟢 🟢 🟢 All cypress tests have passed! 🎉 🎉 🎉
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/15756809644>
> Commit: 58818e09dd83faaa92ee0dad53aab93dcf5f55a5
> <a
href="https://internal.appsmith.com/app/cypress-dashboard/rundetails-65890b3c81d7400d08fa9ee5?branch=master&workflowId=15756809644&attempt=1"
target="_blank">Cypress dashboard</a>.
> Tags: `@tag.List`
> Spec:
> <hr>Thu, 19 Jun 2025 12:11:58 UTC
<!-- end of auto-generated comment: Cypress test results  -->


## Communication
Should the DevRel and Marketing teams inform users about this change?
- [ ] Yes
- [ ] No


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **Bug Fixes**
- Improved handling of empty list data on the first page, ensuring
widgets display correctly when no data is present.
- Enhanced consistency in detecting and rendering empty lists across the
List Widget.

- **New Features**
- Added a utility function to accurately identify fully empty lists,
enabling more predictable widget behavior.
- Introduced an option to handle empty list cases by injecting
placeholder data for consistent widget generation.

- **Tests**
- Added a test to verify the display of "No data to display" message
when the list is empty and confirm no errors occur.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
2025-06-20 09:39:51 +05:30
..
client feat: Implement empty meta widget generation for handling empty data scenarios (#40886) 2025-06-20 09:39:51 +05:30
server feat: Add instanceId to distributed lock keys for multi-instance isolation (#40966) 2025-06-19 12:20:59 +05:30
util